package org.hamcrest.core;

import static org.hamcrest.core.IsEqual.equalTo;
import static org.hamcrest.core.IsInstanceOf.instanceOf;

import org.hamcrest.BaseMatcher;
import org.hamcrest.Description;
import org.hamcrest.Factory;
import org.hamcrest.Matcher;

/**
 * Decorates another Matcher, retaining the behavior but allowing tests
 * to be slightly more expressive.
 *
 * eg. assertThat(cheese, equalTo(smelly))
 * vs  assertThat(cheese, is(equalTo(smelly)))
 */
public class Is<T> extends BaseMatcher<T> {

	private final Matcher<T> matcher;

	public Is(Matcher<T> matcher) {
		this.matcher = matcher;
	}

	@Override
	public boolean matches(Object arg) {
		return matcher.matches(arg);
	}

	@Override
	public void describeTo(Description description) {
		description.appendText("is ").appendDescriptionOf(matcher);
	}

	/**
	 * Decorates another Matcher, retaining the behavior but allowing tests
	 * to be slightly more expressive.
	 *
	 * eg. assertThat(cheese, equalTo(smelly))
	 * vs  assertThat(cheese, is(equalTo(smelly)))
	 */
	@Factory
	public static <T> Matcher<T> is(Matcher<T> matcher) {
		return new Is<T>(matcher);
	}

	/**
	 * This is a shortcut to the frequently used is(equalTo(x)).
	 *
	 * eg. assertThat(cheese, is(equalTo(smelly)))
	 * vs  assertThat(cheese, is(smelly))
	 */
	@Factory
	public static <T> Matcher<T> is(T value) {
		return is(equalTo(value));
	}

	/**
	 * This is a shortcut to the frequently used is(instanceOf(SomeClass.class)).
	 *
	 * eg. assertThat(cheese, is(instanceOf(Cheddar.class)))
	 * vs  assertThat(cheese, is(Cheddar.class))
	 */
	@Factory
	public static Matcher<Object> is(Class<?> type) {
		return is(instanceOf(type));
	}

}
